@AKoprivec You can't completely change a contact property with HubL as if it's a common variable since it will always pulls directly from a database. What exactly is your use case here for changing the property? If you're wanting to change the property within the portal itself that would need to be done through a HubSpot form, the API, or a workflow.
If this answer solved your question, please mark it as the solution.
The code does some math based on the contacts properties gathered by the forms he fills out, and the end result is a number that represents the grade. I want to be able to somehow store that number to be able to use it on diffrent modules.